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Researchers with the International Computer Science Institute in Berkeley, California have unveiled a completed version of their Netalyzr service, a tool designed to detect when your ISP is interfering with your net connection.

The web-based service has been available as a beta since the middle of last year, but it's now set to collect mountains of data for a National Science Foundation-funded project that seeks to determine the state of so-called net neutrality.

"There is all this discussion about network neutrality flying around, and there is fairly little in terms of hard research to show what the reality is - what ISPs really do," Christian Kreibich, a research scientist with the not-for-profit computer science lab, tells The Reg.

"We decided we could build something that normal people could use to better understand what they're facing with their internet use, and as researchers, we also get a data set that lets us analyze this stuff."

Netalyzr - available here - runs inside your browser, but it requires Java. It can't rely on pure JavaScript, Kreibich says, because JavaScript doesn't let the browser create arbitrary network connections. But it does use some JavaScript to detect things such as cookies or framing.

Part of the setup is hosted on Amazon's EC2 service, and Amazon has given the Institute an unspecified amount of money to supplement its use of EC2, but most of the project's funds are provided by the National Science Foundation.

The service attempts to analyze the entire network protocol stack and determine where ISPs - for whatever reason - are actively tinkering with the "normal" flow of traffic. Some of the behavior it's looking for is fairly mundane. It will tell you, for instance, if your ISP forces you to use its own smtp server to send email. Based on preliminary data, Kreibich says, most ISPs do not block the use of personal smtp servers - though some will block smtp servers if you start sending unusually large amounts of email.

But it also looks for more subtle "network management" techniques. There are countless tests involving http proxies, for example. "We test http proxying in quite a bit of detail," Kreibich says. "The correct behavior of the http cache - caught up in most of these proxies - is crucial to your web-surfing experience. We have to be able to rely on the fact that when a content publisher pushes out new content, you aren't getting old stuff."

The service also performs extensive DNS tests - a rarity among other network-analysis services along these lines - looking at both ISP-run DNS services or third-party services such as OpenDNS. It will tell you, for instance, when your DNS service is redirecting mistyped urls or email addresses. Early tests indicate that url redirection is fairly common.

Even if you have no interest in using the service for your own benefit, Kreibich and his team are urging netizens to run the service simply so that the institute can gather additional data for its study. The study is open-ended. Krebich is unsure when the results will be publicly released. ®